@Book{xie2015,
  title = {Dynamic Documents with {R} and knitr},
  author = {Yihui Xie},
  publisher = {Chapman and Hall/CRC},
  address = {Boca Raton, Florida},
  year = {2015},
  edition = {2nd},
  note = {ISBN 978-1498716963},
  url = {http://yihui.org/knitr/},
}
@Manual{dplyr2020,
    title = {dplyr: A Grammar of Data Manipulation},
    author = {Hadley Wickham and Romain Fran?ois and Lionel Henry and Kirill Müller},
    year = {2020},
    note = {R package version 1.0.0},
    url = {https://CRAN.R-project.org/package=dplyr},
  }